The effect of valacyclovir on secondary prevention of congenital cytomegalovirus infection.

It has been established recently that oral valacyclovir 8g/day reduces significantly the vertical CMV transmission rate in pregnancies with primary Cytomegalovirus (CMV) infection acquired periconceptionally or during the first trimester. Aim of the present study is to expand the result of the previous studies by including any recent cohort study on the topic. MEDLINE, Scopus, Cochrane Central Register of Controlled Trials (Central), the US Registry of clinical trials (www.clinicaltrials.gov) and grey literature sources were searched. Randomized controlled trials and cohort studies administering oral valacyclovir 8g/day in pregnancies with primary CMV infection acquired periconceptionally or during the first trimester were included. Cochrane's Risk of Bias 2 and Robins I tools were used for the risk of bias assessment. The result of amniocentesis was the primary outcome of interest. Two-stages individual patient data meta-analysis was performed and a subgroup analysis was carried out, assessing separately the periconceptional period and the first trimester infections. Four studies were included in the analysis (n = 860 participants). Valacyclovir reduced the vertical transmission rate, adjusted odds ratio (a0R) = 0.39 (95 % CI 0.25-0.59). This reduction was apparent both for periconceptional period aOR = 0.30 (95 % CI 0.13-0.68) and first trimester aOR = 0.47 (95 % CI 0.28-0.78) infections. Valacyclovir also reduced the rate of neonatal infection, a0R = 0.45 (95 % CI 0.25-0.83), both in periconceptional period aOR = 0.42 (95 % CI 0.20-0.90)] and in first trimester aOR = 0.54 (95 % CI 0.29-0.99) infections. Oral valacyclovir (8 g/day) reduces the vertical transmission rates of CMV following primary maternal infection acquired periconceptionally or in the first trimester.